This invention relates to a combined gear change and brake control unit for a bicycle. More precisely, this invention relates to a combined unit of the type described by the Applicant in document EP 0 504 118, which is incorporated by reference herein as if fully set forth. This document describes a combined control unit comprising a support body connected to a brake control lever pivoting around a first axis and a gear change control unit connected to the support body. This control unit comprises a gear change lever pivoting on a second axis, orthogonal with respect to the first axis, for shifting the gear. The gear change lever is arranged immediately behind the brake control lever and is free to oscillate in the same direction as the latter lever to prevent obstructing the brake control movement.
The previously described unit comprises a shaft turnable around said second axis, co-operating with a control cable of a derailleur. The rotation of the shaft is controlled by a ratchet mechanism, comprising a gear solidly fastened to the shaft. The gear change lever controls the rotation of the shaft via a meshing unit which meshes said gear. In the known solution, the meshing unit is pivotally connected to a connecting element, which is mounted on the shaft so that it is free to turn with respect to the second axis. The gear change lever is carried so to oscillate on the meshing unit. In home conditions, the meshing unit is not in contact with the gear teeth. When the gear change lever oscillates around said second axis, the lever must travel a small angular stroke to take the meshing unit into contact with the teeth. After this small idle stroke, the rotation movement of the gear change lever produces a rotation which amplitude is equal to the one of the shaft thanks to the contact between the meshing unit and the teeth.
The objective of this invention is to provide a gear change control unit which is constructively more simple and cost-effective than the known solution, reducing the angular stroke of the gear change lever required to take the meshing unit into contact with the teeth.
According to this invention, these objectives are attained by means of a combined control unit which characteristics are described in the main claim.